The story of Acoustic Monitoring International began in 1982, when Babcock and Wilcox developed sensors for leak detection for high-pressure boilers. After successful yet costly attempts at re-applying existing technologies to steam boiler leak detection, B&W contracted with Hartford Steam Boiler Inspection Technologies to design a special system to their particular specifications. HSBIT’s Micheal R. Shaw was given the task of designing the system—the ALL™ Acoustic Leak Locator.

After the initial installation of the ALL™ system at Alabama Power’s Gaston Station in 1991, B&W purchased HSBIT, and created TotalSCOPE Products and Services for boiler operating efficiency. Mike Shaw moved to Babcock & Wilcox at this time to continue his work with the ALL™ system.

In 1997, B&W sold the assets of the ALL™ System to Micheal R. Shaw, and Acoustic Monitoring International, Inc. was born.

AMI immediately began servicing units all over the world that were under B&W’s warranty, and continues to provide parts for all existing systems.

Since its inception, Acoustic Monitoring International has established over 35 new installations of the ALL™ system. With over 2,000 sensors in service in over 10 different countries, AMI’s ALL™ system has been thoroughly field-tested and is extremely reliable. AMI is constantly improving the system; the Acoustic Leak Locator is in its fourth generation.

Acoustic Monitoring International, Inc.–Listening is our business.

• Telephone (330) 305-1422
• E-Mail sales@acousticmonitoring.com
• FAX (330) 494-9822
• Postal Mail< 6707 Harbor Drive N.W. Canton, Ohio 44718 USA

The signal is sent into the self-contained Acoustic Leak Locator (ALL™) system where acoustic signal amplification and signal conditioning is completed for suitable processing. The ALL™ system’s Dual Signal Processing Unit receives the analog acoustic activity signal, processes it and compares it to preset levels and timing parameters. The results are available to the plant’s existing computer system in your required format (as 4-20 mA signal level, alarm relays, and RS232 serial i/o) for graphic display and alarms.

ALL™ provides all the data needed for a clear and accessible visual display of acoustic activity. Levels of alert are predetermined, so that when there is a significant change in activity on any channel you can know a leak has occurred.

When a pressurized fluid such as steam or water escapes through a leak in piping, valves, or feedwater tubes, it generates acoustic emissions which travel through the component’s structure. Small holes generate high frequency acoustic emissions (above the audio frequency range) as the hole increases in size the low frequency complement of the acoustic emission increase and the airborne noise can be heard.

To detect the acoustic emissions early, the structure-borne waveguide is connected to the component to be monitored. The waveguide serves two functions: (1) it couples the acoustic emissions from the component to the sensing device and (2) it protects the electronic sensing device from the high temperature of the component being monitored.

The sensing device is a piezoelectric crystal which converts the acoustic emission signals to low energy electrical signals.

To sense the sound in a boiler, AMI has designed acoustic sensors mounted on the ends of waveguides. The waveguides are mounted on boiler access doors, observation doors, or unused sootblowers ports. The waveguide provides a smooth continuous acoustic path (much like an ear canal) to the sensor and provides thermal protection by eliminating the direct radiant heat of combustion that could overheat the sensor. A secondary purpose of the waveguide is to prevent flyash or wash water from directly contacting the sensor diaphragm. The waveguides are either welded directly to a door or attached with a special fixture and oriented to place the acoustic sensors in as nearly a vertical position as possible.
The sensor is a specially designed pressure transducer for detection of leaks in high pressure and/or high temperature environments on the gas side of furnaces and convection passes of boilers. It is a highly sensitive pressure transducer utilizing piezoelectric crystals with acceleration compensation circuitry to minimize extraneous signals due to mechanical vibrations. Due to the sensor’s operating environment, its mechanical and electrical design was carefully designed to meet the following requirements:

A rigid mechanical construction to avoid mechanical strains on the piezoelectric crystal that could induce unknown changes in sensitivity.

Capability of absorbing very severe thermal shocks (550°F/sec.) without any sensor damage. High sensitivity coupled with extremely high resolution for detection of high frequency noise (leaks).

High degree of reliability in presence of corrosive gas in the boiler environment.